Headrest support structure

Abstract

To obtain a headrest support structure which can easily and steplessly adjust a height of a headrest in a seat vertical direction.SOLUTION: A leg part 22A of a headrest stay 22 is inserted into a cylindrical member 32. A recess 32X which is annularly and recessively formed along a circumferential direction is formed at an internal peripheral face 32N of the cylindrical member 32. The recess 32X comprises a pair of vertical tapered parts 32B which are inclined so as to gradually narrow mutual vertical opposing intervals toward a recess bottom side from its opening end side. A plurality of balls 34 arranged in the recess 32X are aligned in a circumferential direction of the internal peripheral face 32N of the cylindrical member 32, contact with both the cylindrical member 32 and the leg part 22A of the headrest stay 22, hold the leg part 22A by friction forces, and when the leg part 22A is vertically moved, become rotatable while being regulated in relative displacements in a vertical direction with respect to the internal peripheral face 32N of the cylindrical member 32 by a pair of the vertical tapered parts 32B.SELECTED DRAWING: Figure 2B

Description

[Technical Field]

[0001] The present invention relates to a headrest support structure. [Background technology]

[0002] Patent Document 1 below discloses a locking structure capable of locking and unlocking. This locking structure includes a cylinder, a rod-shaped member inserted into the cylinder, a tapered member fitted into the cylinder so as to be movable along the axial direction of the cylinder and having a tapered portion, an elastic body that biases and supports the tapered member in a direction in which the inner diameter of the tapered portion gradually increases, and a locking member. The locking member is accommodated in the space between the tapered member and the rod-shaped member, and is configured to be pressed against the tapered portion as the rod-shaped member moves in a direction in which the inner diameter of the tapered portion gradually decreases, thereby abutting against the inner wall of the accommodation space and applying a load to the rod-shaped member. With this configuration, when the rod-shaped member moves in the direction in which the inner diameter of the tapered portion gradually decreases, the locking member engages the lock. By moving the tapered member in the direction in which the inner diameter of the tapered portion gradually decreases against the elastic force of the elastic body, the load imposed by the locking member is released, and the lock can be easily released. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-260446 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above-mentioned prior art locking structure is applied to an actuator that lifts the rear end of a car hood, but since it cannot be adjusted continuously, there is room for improvement if it is to be applied to a headrest support part.

[0005] SUMMARY OF THE INVENTION In consideration of the above, an object of the present invention is to provide a headrest support structure that allows for easy and stepless adjustment of the height of the headrest in the up-down direction of the seat. [Means for solving the problem]

[0006] The headrest support structure of the present invention described in claim 1 comprises a headrest stay having a leg portion extending downward from inside a headrest body, a cylindrical member formed in a cylindrical shape and through which the leg portion is inserted, and a circular recess formed along the circumferential direction on either the inner peripheral surface of the cylindrical member or the outer peripheral surface of the leg portion. a pair of upper and lower tapered portions that are inclined so as to gradually narrow the opposing gap between them from the opening end side of the recess toward the recessed bottom side; The recesses are arranged in the circumferential direction of one of the cylindrical members, and contact both the cylindrical member and the leg portion, and hold the leg portion by frictional force. When the leg portion is moved up and down, When one of the two moves upward relative to the other of the inner peripheral surface of the cylindrical member and the outer peripheral surface of the leg portion, the lower tapered portion of the pair of upper and lower tapered portions restricts downward relative displacement with respect to the one of the two, while allowing rotation, and when the one of the two moves downward relative to the other, the upper tapered portion of the pair of upper and lower tapered portions restricts upward relative displacement with respect to the one of the two, while allowing rotation. and a plurality of balls.

[0007] According to the above configuration, the leg portion of the headrest stay is inserted into the cylindrical member. A recess formed in an annular concave shape along the circumferential direction is provided on one of the inner peripheral surface of the cylindrical member and the outer peripheral surface of the leg portion. In addition, the headrest support structure having the above configuration is Concave Department The recess has a pair of upper and lower tapered portions that are inclined so that the vertical opposing distance between them gradually narrows from the open end side to the recessed bottom side. The balls arranged in the recess are aligned in one circumferential direction, and contact both the cylindrical member and the leg portion, and hold the leg portion by frictional force. Furthermore, when the leg portion is moved up and down, When one of the two moves upward relative to the other of the inner surface of the tubular member and the outer surface of the leg, the lower of the pair of upper and lower tapered portions restricts downward relative displacement with respect to the one of the two, while allowing rotation, and when one of the two moves downward relative to the other, the upper of the pair of upper and lower tapered portions restricts upward relative displacement with respect to the one of the two, while allowing rotation. This allows the height of the headrest in the up-down direction of the seat to be easily and continuously adjusted.

[0010] Claim 2 In the headrest support structure of the present invention described above, in the configuration described in claim 1, the plurality of balls aligned in one circumferential direction are provided in multiple sets aligned in the axial direction of the leg portion.

[0011] According to the above configuration, by changing the number of balls arranged circumferentially on the inner surface of the tubular member in the axial direction of the leg portion, the operating force required for the up and down movement of the headrest stay can be easily adjusted.

[0012] Claim 3 The headrest support structure of the present invention described in claim 1 or claim 2 2 In the configuration described above, a ring member is provided which is formed in an endless string shape passing through the centers of the plurality of balls arranged in one circumferential direction, has elasticity, and can elastically return to the shape of the assembled state when elastically deformed.

[0013] According to the above configuration, when placing a plurality of balls in the recess, the endless string-like ring member allows the plurality of balls to be easily placed in the appropriate positions within the recess.

[0020] Claim 4 The headrest support structure of the present invention described in claim 1 ~ Claim 3 In the configuration described in any one of the above, there is an upper bushing through which the leg portion is inserted and which is provided on the outer periphery of the tubular member, and a lower bushing adjacent to the lower end of the tubular member on the lower side and through which the leg portion is inserted and which is provided on the lower end side of the upper bushing so as to be able to engage and disengage.

[0021] According to the above configuration, during assembly, the tubular member is first placed inside the upper bush, the upper bush is then engaged with the lower bush, and the legs of the headrest stay can then be inserted through the upper and lower bushes. Disassembly is also possible by releasing the engagement between the upper and lower bushes. [Effects of the Invention]

[0022] As described above, the headrest support structure of the present invention has the excellent effect of allowing the height of the headrest in the up-down direction of the seat to be easily and continuously adjusted. [Brief explanation of the drawings]

[0023] [Figure 1]1 is a simplified view showing an upper part of a vehicle seat provided with a headrest support structure according to a first embodiment, as viewed obliquely from above and in front. [Figure 2A] 2 is a plan cross-sectional view showing a bush and the like cut at a height position along the top surface of a locking device applied to the headrest support structure of FIG. 1. FIG. [Figure 2B] FIG. 2B is a longitudinal cross-sectional view taken along line 2B-2B in FIG. 2A. [Figure 3] 10 is a schematic cross-sectional view for explaining the balance of forces when the headrest is in a stationary state. FIG. [Figure 4] 10 is a schematic cross-sectional view showing the force relationship when the headrest stay is raised. FIG. [Figure 5] 5 is a schematic cross-sectional view showing the force relationship during a collision. FIG. [Figure 6] FIG. 10 is a vertical cross-sectional view showing a headrest support structure according to a second embodiment. [Figure 7] FIG. 7 is a vertical cross-sectional view for explaining the assembly of the balls in FIG. 6. [Figure 8] FIG. 10 is a vertical cross-sectional view showing a headrest support structure according to a third embodiment. [Figure 9] FIG. 10 is a vertical cross-sectional view showing a headrest support structure according to a fourth embodiment. [Figure 10] FIG. 10 is an exploded cross-sectional view showing a part of the headrest support structure of FIG. 9. [Figure 11] FIG. 13 is a bottom view showing the lower end portion side of the headrest stay in a modified example of the fourth embodiment, as viewed from below. [Figure 12] FIG. 10 is a perspective view showing a headrest support structure according to a fifth embodiment. [Figure 13] FIG. 10 is a vertical cross-sectional view showing a headrest support structure according to a sixth embodiment. [Figure 14] FIG. 14 is a plan view showing the fastening member of FIG. 13 alone. [Figure 15] FIG. 13 is a vertical cross-sectional view showing a modified example of the sixth embodiment. [Figure 16]FIG. 13 is a vertical cross-sectional view showing a headrest support structure according to a seventh embodiment. [Figure 17] FIG. 17 is an exploded cross-sectional view showing a part of the headrest support structure of FIG. [Figure 18] FIG. 13 is a simplified view showing the upper part of a vehicle seat provided with a headrest support structure according to a ninth embodiment, as viewed obliquely from above and in front. [Figure 19A] 19 is a schematic horizontal cross-sectional view showing a state in which the locking device of FIG. 18 locks the leg portion. FIG. [Figure 19B] 19B is a schematic horizontal cross-sectional view showing a state in which the operating lever has been operated in the unlocking direction from the state of FIG. 19A. FIG. [Figure 19C] 19C is a schematic horizontal cross-sectional view showing a state in which the operating lever is further operated in the unlocking direction from the state of FIG. 19B and the lock is released. FIG. [Figure 19D] 19D is a schematic horizontal cross-sectional view showing a state in which the operating lever is operated in a direction opposite to the unlocking direction from the state of FIG. 19C. FIG. [Figure 19E] 19D, and FIG. 19C is a schematic horizontal cross-sectional view showing a state in which the operating lever is further operated in the direction opposite to the unlocking direction. [Figure 20A] 19 is a perspective view for explaining an assembly procedure applied to the headrest support structure of FIG. 18. FIG. [Figure 20B] 20B is a perspective view showing a state in which a holder is welded to the upper frame of FIG. 20A. FIG. [Figure 20C] FIG. 20C is a perspective view showing a state in which a bush is inserted into the holder of FIG. 20B. [Figure 20D] 20D is a simplified perspective view showing a state in which the lower part of the locking device is engaged with the bush of FIG. 20C. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0024] [First embodiment] A headrest support structure according to a first embodiment of the present invention will be described with reference to Figures 1 to 5. Note that in these figures, the arrow FR indicates the front side of the seat, the arrow UP indicates the upper side of the seat, and the arrow W indicates the seat width direction (left-right direction of the seat).

[0025] (composition) 1 shows a simplified view of the upper part of a vehicle seat 10 equipped with a headrest support structure 11 according to the first embodiment, viewed from diagonally above the front. The vehicle seat 10 includes a seat cushion (not shown) that supports the buttocks and thighs of a seated occupant, a seat back 12 that supports the back of the seated occupant, and a headrest 20 that supports the head of the seated occupant.

[0026] The seat back 12 is configured such that a back pad (not shown) made of cushioning material is placed on a back frame 14, which is a framework member, and the surface of the back pad is covered with a trim cover 18, which is an upholstery material. The back frame 14 includes a pair of left and right side frames (not shown) extending in the seat back height direction and a long, pipe-like upper frame 14A connecting the upper ends of the pair of left and right side frames. The upper frame 14A is formed in a horizontally elongated, approximately inverted U-shape when viewed from the front of the seat. A pair of left and right cylindrical holders 16 for connecting headrests 20 are fixed by welding to the front part of the upper frame 14A extending in the seat width direction. A cylindrical resin bush 26 is inserted into the holder 16. The upper end of the bush 26 is flange-shaped and exposed at the upper end of the seat back 12.

[0027] The headrest 20 is configured such that a headrest pad (not shown), which is a cushioning material, is placed on top of a headrest stay 22, which is a framework member, and the surface of the headrest pad is covered with a trim cover 24, which is a skin material. The portion of the headrest pad (not shown) covered with the trim cover 24 constitutes the headrest main body 20A. The headrest stay 22 is formed into a substantially inverted U-shape by, for example, bending a metal pipe, and has legs 22A that extend downward from inside the headrest main body 20A. The pair of left and right legs 22A of the headrest stay 22 are inserted into a pair of left and right bushings 26 and are connected to the upper end of the back frame 14 via a pair of left and right holders 16.

[0028] A locking device 30 shown in Fig. 2A is incorporated within the bushing 26. In this embodiment, the locking device 30 is molded integrally with the bushing 26 during injection molding of the bushing 26. Fig. 2A is a plan cross-sectional view showing the bushing 26 and other components cut at a height position along the top surface 32U of the locking device 30, and Fig. 2B is a vertical cross-sectional view taken along line 2B-2B in Fig. 2A. For convenience, Fig. 2B shows the illustrated range of the leg portion 22A of the headrest stay 22 in the up-down direction wider than the illustrated range of the bushing 26 in the up-down direction.

[0029] As shown in FIGS. 2A and 2B, the locking device 30 includes a cylindrical member 32. The upper end surface 32U of the cylindrical member 32 forms the upper surface 32U of the locking device 30. The leg portions 22A of the headrest stays 22 are inserted through the cylindrical member 32. An annular recess 32X is formed in the inner peripheral surface 32N of the cylindrical member 32 along the circumferential direction of the cylindrical member 32. As shown in FIG. 2B, the recess 32X includes a pair of upper and lower tapered portions 32B that are inclined from the open end side toward the recessed bottom side so that the vertically opposing distance between them gradually narrows. The tapered portions 32B connect the small diameter portion 32A and the large diameter portion 32C, which has a larger diameter than the small diameter portion 32A, on the inner peripheral surface 32N of the cylindrical member 32. In this embodiment, the large diameter portion 32C extends along the axial direction of the cylindrical member 32 in the axially intermediate portion of the cylindrical member 32.

[0030] 2A, a plurality of balls 34 are arranged in the circumferential direction of the inner peripheral surface 32N of the cylindrical member 32 within the recess 32X of the cylindrical member 32. As shown in Figures 2A and 2B, the plurality of balls 34 are in contact with both the cylindrical member 32 and the leg portion 22A of the headrest stay 22, and hold the leg portion 22A by frictional force. Furthermore, when the leg portion 22A shown in Figure 2B is moved up and down, the pair of upper and lower tapered portions 32B restricts the relative displacement in the up and down direction with respect to the inner peripheral surface 32N of the cylindrical member 32, and the balls 34 are allowed to rotate.

[0031] 2A, balls 34 adjacent to each other in the circumferential direction are connected to each other by ball connecting members 36. The ball connecting members 36 are provided to prevent the balls 34 from coming apart inside the tubular member 32, and are attached to the balls 34 in an attachment form that maintains the rotatable state of the balls 34.

[0032] As shown in FIG. 2B , the balls 34 arranged in the circumferential direction on the inner peripheral surface 32N of the cylindrical member 32 are arranged in multiple sets in the axial direction of the leg portion 22A. For convenience, the balls 34 arranged in the vertically intermediate portion of the cylindrical member 32 are omitted from FIG. 2B , and a vertical "···" symbol is added above the omitted portion. However, in reality, multiple sets of balls 34 similar to the upper two sets are arranged in the axial direction of the leg portion 22A in the omitted portion. The number of sets of balls 34 is a factor that contributes to adjusting the operating force required for the vertical movement of the headrest stay 22 and is set at the time of design. In this embodiment, a portion of the ball connecting member 36 is interposed between adjacent balls 34 in the vertical direction to prevent interference between adjacent balls 34 in the vertical direction. The balls 34 arranged in the uppermost and lowermost rows of the balls 34 are in contact with the tapered portion 32B.

[0033] Meanwhile, the lower end of the leg portion 22A of the headrest stay 22 is positioned lower than the lower ends of the locking device 30 and the bush 26. A small protrusion 22A1 is formed at a predetermined circumferential position on the lower end of the leg portion 22A of the headrest stay 22, protruding slightly radially outward compared to other portions. The small protrusion 22A1 is an element that makes it difficult for the leg portion 22A of the headrest stay 22 to come off the locking device 30. The small protrusion 22A1 is set to a degree that allows the headrest 20 to be pulled out of the locking device 30 when the user pulls up the headrest 20 with a certain amount of force. When assembling the headrest stay 22 to the locking device 30 and the bush 26, a corresponding pushing force is required for the small protrusion 22A1 to pass through the ball 34, but the required pushing force (insertion force) decreases after the small protrusion 22A1 has passed through the ball 34.

[0034] In order to suppress the influence of heat on the operating force, the headrest stay 22, the cylindrical member 32 and the ball 34 are made of steel, for example.

[0035] (Supplementary explanation of basic principles) Next, a supplementary explanation of the basic principle will be given with reference to Figures 3 to 5. Note that Figures 3 to 5 are schematic diagrams for explaining the basic principle, and for convenience, the same components as those explained in the first embodiment are given the same reference numerals. In addition, in Figures 3 and 4, the dashed dotted line CL indicates the central axis of the leg portion 22A of the headrest stay 22.

[0036] First, the balance of forces when the headrest 20 is in a stationary state will be described with reference to FIG.

[0037] In FIG. 3, the mass of the ball 34 is m b The mass of the entire headrest 20 including the headrest stay 22 is m s and the gravitational acceleration is g. The maximum static friction force at the contact portion between the ball 34 and the large diameter portion 32C of the cylindrical member 32 is f w The maximum static friction force at the contact portion between the ball 34 and the leg portion 22A of the headrest stay 22 is f s Furthermore, the normal force acting on the ball 34 by the large diameter portion 32C of the cylindrical member 32 is N w is the normal force acting on the ball 34 by the leg 22A of the headrest stay 22, and N s Let's say.

[0038] From the equation for the balance of the ball 34, the following (Equation 1) and (Equation 2) are established. (m b +m s )g=f w +f s ...(Formula 1) N s =N w ...(Formula 2)

[0039] The static friction coefficient at the contact portion between the ball 34 and the large diameter portion 32C of the cylindrical member 32 is μ w and the static friction coefficient at the contact portion between the ball 34 and the leg portion 22A of the headrest stay 22 is μ s Then, the following (Equation 3) and (Equation 4) are established based on the friction equation. f s =μs N s ...(Formula 3) f w =μ w N w ...(Formula 4)

[0040] From the above (Equation 1) to (Equation 4), the following (Equation 5) is established. (m b +m s )g=(μ s +μ w )N s ...(Formula 5) From the above (Equation 5), N s When this is calculated, the following (Equation 6) is obtained. N s =((m b +m s ) / (μ s +μ w ))g...(Formula 6) The above (Equation 6) indicates the condition under which the ball 34 does not fall.

[0041] Furthermore, from the equation for balance of the headrest stay 22, the following (Equation 7) is established. f s =m s g...(Equation 7)

[0042] From the above (Equation 3) and (Equation 7), the following (Equation 8) is established. μ s N s =m s g...(Equation 8) From the above (Equation 8), N s When this is calculated, the following (Equation 9) is obtained. N s =(m s / μ s )g...(Equation 9) The above (Equation 9) indicates the condition under which the headrest stay 22 does not fall. By satisfying this condition, the headrest 20 will stay in place without falling even if an occupant adjusting the height of the headrest 20 shown in FIG. 1 moves away from the headrest 20.

[0043] Next, the case where the headrest stay 22 is raised (during normal use) will be described with reference to Fig. 4. Note that in Fig. 4, for ease of viewing, the inclination angle of the tapered portion 32B is shown differently from that in Fig. 3.

[0044] In FIG. 4, the normal force acting on the ball 34 by the upper tapered portion 32B of the cylindrical member 32 is N T The kinetic friction force at the contact portion between the ball 34 and the large diameter portion 32C of the cylindrical member 32 is expressed as f' w and the kinetic friction force at the contact portion between the ball 34 and the upper tapered portion 32B of the cylindrical member 32 is f' T Other symbols are the same as in Figure 3.

[0045] Here, the coefficient of dynamic friction at the contact portion between the ball 34 and the large diameter portion 32C of the cylindrical member 32 shown in FIG. 4 is μ' w and the coefficient of dynamic friction at the contact portion between the ball 34 and the upper tapered portion 32B of the cylindrical member 32 is μ' T Then, μ s >μ' T +μ' w Therefore, if the radius of the ball 34 is r, the following (Equation 10) holds. f s r>(f' T +f' w )r...(Equation 10) That is, when a force F (operating force by the occupant) equal to or greater than a predetermined value is applied to lift the headrest stay 22 during normal use, the ball 34 rotates in the direction of arrow R.

[0046] Next, the force relationship during a collision will be described with reference to FIG.

[0047] In FIG. 5, the maximum static friction force at the contact portion between the ball 34 and the upper tapered portion 32B of the cylindrical member 32 is f T Other symbols are the same as in Figure 4.

[0048] Here, if the inclination angle of the upper tapered portion 32B with respect to the vertical direction in FIG. 5 is θ, the following (Equation 11) is established. f s cosθ+f T >m b g cos θ (Equation 11)

[0049] That is, in the event of a collision, the leg 22A of the headrest stay 22 attempts to rise in a short time, and the coefficient of friction between the tubular member 32 and the ball 34 remains the static coefficient of friction, so that the ball 34 attempts to rise up the upper tapered portion 32B, and the so-called wedge effect stops the rise of the leg 22A.

[0050] (Actions and Effects) Next, the operation and effects of this embodiment will be described.

[0051] As shown in FIGS. 2A and 2B , the leg portions 22A of the headrest stays 22 are inserted through the tubular member 32. An annular recess 32X is formed in the inner circumferential surface 32N of the tubular member 32 along its circumferential direction, and the recess 32X has a pair of upper and lower tapered portions 32B that are inclined so that the vertical spacing between the recesses 32X gradually narrows from the open end toward the bottom. A plurality of balls 34 arranged in the recess 32X are aligned along the circumferential direction of the inner circumferential surface 32N of the tubular member 32. The balls 34 contact both the tubular member 32 and the leg portions 22A of the headrest stays 22, holding the leg portions 22A by frictional force. Furthermore, when the leg portions 22A are moved up and down, the pair of upper and lower tapered portions 32B restrict their vertical displacement relative to the inner circumferential surface 32N of the tubular member 32, allowing them to rotate. This allows for easy, stepless adjustment of the vertical height of the headrest 20 shown in FIG. 1 .

[0052] 2B, in this embodiment, the plurality of balls 34 arranged in the circumferential direction of the inner circumferential surface 32N of the cylindrical member 32 are provided in multiple sets arranged in the axial direction of the leg portion 22A. Here, by changing the number of the plurality of balls 34 arranged in the circumferential direction of the inner circumferential surface 32N of the cylindrical member 32 arranged in the axial direction of the leg portion 22A, the operating force required for the up and down movement of the headrest stay 22 can be easily adjusted.

[0053] As described above, the headrest support structure 11 of this embodiment has the excellent effect of allowing the height of the headrest in the up-down direction of the seat to be easily and continuously adjusted.

[0054] [Second embodiment] Next, a headrest support structure according to a second embodiment of the present invention will be described with reference to Figures 6 and 7. Figure 6 shows a vertical cross-sectional view of a headrest support structure 40 according to the second embodiment, and Figure 7 shows a vertical cross-sectional view for explaining the assembly of a ball 46. Note that in Figure 6, only the outline of the leg portion 22A of the headrest stay 22 is shown by a two-dot chain line for convenience. Furthermore, since the headrest stay 22 of the second embodiment has the same configuration as the headrest stay 22 of the first embodiment (see Figures 1 to 2B), the same reference numerals are used and description thereof will be omitted.

[0055] As shown in FIG. 6, the headrest support structure 40 includes a first bushing 42 made of resin as a cylindrical member formed into a cylindrical shape. In this embodiment, the first bushing 42 is made of resin as an example, but it may also be made of steel. The leg portion 22A of the headrest stay 22 is inserted into the first bushing 42. A brim-shaped flange portion 42F that protrudes radially outward is formed at the upper end of the first bushing 42. A locking portion 42K is formed at the lower portion of the first bushing 42. A cylindrical second bushing 44 made of steel is arranged on the outer circumferential side of the first bushing 42, between the flange portion 42F and the locking portion 42K.

[0056] The inner circumferential surface 42N of the first bushing 42 is provided with a recess 42X formed in an annular concave shape along the circumferential direction. The recess 42X has a pair of upper and lower tapered portions 42B that are inclined so that the vertically opposing distance between them gradually narrows from the open end side toward the concave bottom side. The tapered portions 42B connect the small diameter portion 42A and the large diameter portion 42C, which has a larger diameter than the small diameter portion 42A, on the inner circumferential surface 42N of the first bushing 42. In this embodiment, the large diameter portion 42C is formed in a linear shape that forms a circle in a plan view, and the recess 42X is formed in a horizontal V-shape in a vertical cross section. Two recesses 42X are formed at an interval from each other in the vertical middle portion of the first bushing 42.

[0057] A plurality of balls 46 are arranged in the recesses 42X of the inner peripheral surface 42N of the first bushing 42, aligned in the circumferential direction of the inner peripheral surface 42N of the first bushing 42. Note that, for ease of viewing, in Figures 6 and 7, two balls 46 are illustrated in each recess 42X for convenience, but in reality, a large number of balls 46 are arranged in each recess 42X aligned in the circumferential direction. The plurality of balls 46 contact both the first bushing 42 and the leg portion 22A of the headrest stay 22, hold the leg portion 22A by frictional force, and further, when the leg portion 22A is moved up and down, the pair of upper and lower tapered portions 42B restricts the relative displacement in the up and down direction with respect to the inner peripheral surface 42N of the first bushing 42, allowing the balls 46 to rotate.

[0058] In this embodiment, an endless string-like ring member 48 is provided that passes through the centers of multiple balls 46 arranged circumferentially on the inner peripheral surface 42N of the first bushing 42. During manufacturing, both ends of the string-like member that passes through the centers of the multiple balls 46 are joined to form the annular ring member 48. The ring member 48 is elastic and can elastically return to its assembled shape when elastically deformed. The balls 46 and ring member 48 form a bracelet-like ball module 49. When the ball module 49 made up of the balls 46 and ring member 48 is placed in the recess 42X of the first bushing 42, the ball module 49 shown in FIG. 7 is inserted from the outside to the inside of the first bushing 42 while deforming the ring member 48, and is finally placed as shown in FIG. 6.

[0059] In this embodiment, the balls 46 are arranged in the circumferential direction on the inner circumferential surface 42N of the first bushing 42, and multiple sets (for example, two sets) of balls 46 are arranged in the axial direction of the leg portion 22A.

[0060] The configuration of the second embodiment described above also provides substantially the same functions and effects as the first embodiment. Furthermore, in the second embodiment, when placing multiple balls 46 in recess 42X, the endless string-like ring member 48 allows the multiple balls 46 to be easily placed in appropriate positions within recess 42X.

[0061] [Third embodiment] Next, a headrest support structure according to a third embodiment of the present invention will be described with reference to Fig. 8, with reference to Fig. 1. Fig. 8 shows a vertical cross-sectional view of a headrest support structure 50 according to the third embodiment.

[0062] As shown in Fig. 8, the headrest support structure 50 has a headrest stay 52 with a leg portion 52A extending downward from inside the headrest main body 20A (see Fig. 1). An outer peripheral surface 52G of the leg portion 52A of the headrest stay 52 is provided with a recess 52X formed in an annular, concave shape along the circumferential direction of the outer peripheral surface 52G of the leg portion 52A. The recess 52X has a pair of upper and lower tapered portions 52T that are inclined from the open end side toward the concave bottom side so that the gap between the upper and lower opposing portions gradually narrows. The recess 52X is formed in a horizontal V-shape in a vertical cross section, and for example, three recesses 52X are formed at intervals from each other in the vertical direction.

[0063] The headrest support structure 50 also includes a first bushing 54 as a cylindrical member formed in a cylindrical shape and through which the leg portion 52A of the headrest stay 52 is inserted. A brim-shaped flange portion 54F that protrudes radially outward is formed at the upper end of the first bushing 54. A locking portion 54K is also formed at the lower portion of the first bushing 54. A cylindrical second bushing 55 made of steel is disposed on the outer circumferential side of the first bushing 54, between the flange portion 54F and the locking portion 54K.

[0064] A plurality of balls 56 are arranged in the circumferential direction of the outer peripheral surface 52G of the leg portion 52A of the headrest stay 52 within the recess 52X of the headrest stay 52. ​​The plurality of balls 56 contact both the first bush 54 and the leg portion 52A of the headrest stay 52 and hold the leg portion 52A by frictional force, and further, when the leg portion 52A is moved up and down, the pair of upper and lower tapered portions 52T restricts the relative displacement in the up and down direction with respect to the outer peripheral surface 52G of the headrest stay 52 while allowing the leg portion 52A to rotate.

[0065] In addition, in this embodiment, an endless string-like ring member 58 is provided that passes through the centers of the plurality of balls 56 that are arranged in the circumferential direction on the outer peripheral surface 52G of the leg portion 52A of the headrest stay 52. ​​The ring member 58 is elastic and can elastically return to the shape of the assembled state when it is elastically deformed.

[0066] In this embodiment, the balls 56 are arranged in the circumferential direction on the outer peripheral surface 52G of the leg portion 52A of the headrest stay 52, and multiple sets (three sets, for example) of balls 56 are arranged in the axial direction of the leg portion 22A.

[0067] The configuration of the third embodiment described above also provides substantially the same functions and effects as those of the second embodiment. Note that by changing the number of recesses 52X in which the plurality of balls 56 are arranged, the operating force required to move the headrest stay 52 up and down can be adjusted.

[0068] [Fourth embodiment] Next, a headrest support structure according to a fourth embodiment of the present invention will be described with reference to Figures 9 and 10. Figure 9 shows a vertical cross-sectional view of a headrest support structure 60 according to the fourth embodiment. Figure 10 shows an exploded cross-sectional view of a portion of the headrest support structure 60. The configuration of the fourth embodiment shown in Figures 9 and 10 is substantially the same as that of the first embodiment, except for the points described below. Therefore, components that are substantially the same as those in the first embodiment will be assigned the same reference numerals and descriptions thereof will be omitted.

[0069] 1 to 2B in that, instead of the small protrusions 22A1 of the leg portions 22A of the headrest stays 22 in the first embodiment shown in Fig. 2B etc., the leg portions 62A of the headrest stays 62 are formed with notches 62A1 shown in Fig. 9, but otherwise the headrest stays 22 have the same configuration as the headrest stays 22 of the first embodiment. The notches 62A1 shown in Fig. 9 are intended to prevent the leg portions 62A of the headrest stays 62 from coming off in the event of a collision (impact). This point will be described later.

[0070] The headrest support structure 60 includes a locking device 30 similar to the locking device 30 in the first embodiment (see FIGS. 2A and 2B). A resin upper bushing 64 is provided on the outer periphery of a cylindrical member 32 of the locking device 30. The upper bushing 64 is substantially cylindrical, and a leg portion 62A of the headrest stay 62 is inserted through the upper bushing 64. A thick, annular stopper portion 64S is formed at the upper end of the upper bushing 64.

[0071] A locking member 66 is provided on the stopper portion 64S. The locking member 66 is plate-shaped overall and has a push knob 66A on part of the upper part of the stopper portion 64S. The push knob 66A can be pushed in a direction toward the axis of the upper bush 64 against the biasing force of a return spring (not shown). The locking member 66 also has a through-hole 66H through which the leg portion 62A of the headrest stay 62 passes in a plan view, and is also provided with a locking portion 66B that forms part of the periphery of the through-hole 66H and can come into contact with or separate from the leg portion 62A of the headrest stay 62.

[0072] As a result, if the leg 62A of the headrest stay 62 is about to come loose upward from the upper bush 64, the locking portion 66B fits into the notch 62A1 on the lower end side of the leg 62A to prevent it from coming loose.

[0073] A cylindrical body portion 64A is formed continuously below the intermediate portion between the inner and outer circumferential ends of the stopper portion 64S. A crushed rib 64R is formed on the lower surface of the stopper portion 64S, near the inner circumferential end, protruding toward the upper surface 32U of the cylindrical member 32 and contacting the upper surface 32U of the cylindrical member 32. The crushed rib 64R is used to absorb dimensional variations. Furthermore, a recessed engagement recess 68 that opens toward the axial center of the upper bushing 64 is formed on the lower end side of the body portion 64A.

[0074] Meanwhile, a lower bushing 70 is provided adjacent to the lower end portion 32Z of the tubular member 32 of the locking device 30 on the lower side thereof. The lower bushing 70 is generally cylindrical, and the leg portion 62A of the headrest stay 62 is inserted therethrough. A locking portion 70K is formed at the bottom of the lower bushing 70. A crushing rib 70R is formed at the top of the lower bushing 70, protruding toward the lower end portion 32Z of the tubular member 32 and coming into contact with the lower end portion 32Z of the tubular member 32. The crushing rib 70R is used to absorb dimensional variations.

[0075] Additionally, a locking member 72 having a protruding engagement claw 72A that can engage with and disengage from the engagement recess 68 of the upper bushing 64 is provided at an upper portion of the lower bushing 70 radially outward of the crushing rib 70R. The locking member 72 is formed in an L-shape as a whole and includes a first arm 72B that extends downward from the upper portion where the engagement claw 72A is formed, and a second arm 72C that extends radially outward from the lower end of the first arm 72B. The locking member 72 is biased radially outward from the lower bushing 70 by a return spring (not shown). In a normal state, a terminal portion 72C1 of the second arm 72C protrudes from the outer peripheral surface of the lower bushing 70 and can be pressed toward the axis of the lower bushing 70 (see arrow 72P) against the biasing force of the return spring (not shown).

[0076] When the terminal portion 72C1 of the second piece 72C of the locking member 72 is not pressed, the engagement claw 72A engages with the engagement recess 68 of the upper bushing 64. When the terminal portion 72C1 of the second piece 72C of the locking member 72 is pressed, the engagement claw 72A is released from the engagement recess 68 of the upper bushing 64. As a result, the lower bushing 70 is provided on the lower end side of the upper bushing 64 so as to be able to engage with and disengage from the upper bushing 64.

[0077] Here, the assembly of the headrest support structure 60 shown in Fig. 9 will be described. First, the locking device 30 is inserted from below into the upper bush 64 shown in Fig. 10 (see arrow S1). Next, the lower bush 70 is brought closer to the upper bush 64 and the locking device 30 from below (see arrow S2) so that the engaging claw 72A of the lower bush 70 engages with the engaging recess 68 of the upper bush 64. Finally, as shown in Fig. 9, the leg portion 62A of the headrest stay 62 is inserted from above so as to pass through the axial centers of the upper bush 64, the locking device 30, and the lower bush 70, thereby obtaining the headrest support structure 60 shown in Fig. 11.

[0078] The configuration of the fourth embodiment described above also provides the same effects and advantages as the first embodiment. Furthermore, in the fourth embodiment, when the locking member 72 provided on the lower bushing 70 is pressed, the engagement (lock) between the engagement claw 72A of the locking member 72 and the engagement recess 68 of the upper bushing 64 is released, so that the locking device 30, the upper bushing 64, and the lower bushing 70 can be easily disassembled.

[0079] [Modification of the fourth embodiment] Next, a modified example of the fourth embodiment will be described with reference to Fig. 11. Fig. 11 shows a bottom view of the lower end side of the leg portion 74A of the headrest stay 74 in the modified example of the fourth embodiment, as viewed from below. The headrest stay 74 has the same configuration as the headrest stay 62 shown in Fig. 9, except for the points described below.

[0080] In the configuration of the above-described fourth embodiment, notches 62A1 are formed on the lower end sides of the leg portions 62A of the headrest stays 62 to prevent the leg portions 62A from coming off during a collision (impact), but instead of such notches 62A1, pin mounting portions 74A1 shown in FIG. 11 may be provided and a pin 75 may be attached to the pin mounting portion 74A1. As an example, the pin 75 is bent into a substantially hat shape when viewed from the bottom in FIG. 11. In this modification of the fourth embodiment, when the headrest stay 74 is pulled up by more than a predetermined amount during a collision or the like, the pin 75 hits the bottom side of the lower bush 70 (see FIG. 9) and stops the leg portions 74A from coming off, thereby preventing the leg portions 74A of the headrest stays 74 from coming off.

[0081] [Fifth embodiment] Next, a headrest support structure according to a fifth embodiment of the present invention will be described with reference to Fig. 12. Fig. 12 shows a perspective view of a headrest support structure 76 according to the fifth embodiment. In Fig. 12, components that are substantially the same as those in the first embodiment are given the same reference numerals.

[0082] 12, in the fifth embodiment, the locking device 30 is disposed in substantially the same position as the holder 16 (see FIG. 1) in the first embodiment and is directly joined to the upper frame 14A of the back frame 14, and the leg portion 22A of the headrest stay 22 is inserted into such locking device 30. With such a fifth embodiment, substantially the same actions and effects as those of the first embodiment described above can be obtained.

[0083] [Sixth embodiment] next , th The headrest support structure according to the sixth embodiment will be described with reference to FIGS. 13 and 14 while also referring to FIG. The sixth embodiment is not an embodiment of the present invention but a reference example. FIG. 13 shows a vertical cross-sectional view of a headrest support structure 80 according to a sixth embodiment.

[0084] The headrest stay 62 shown in Fig. 13 has the same configuration as the headrest stay 62 in the fourth embodiment (see Fig. 9). The leg portion 62A is inserted into a cylindrical resin bushing 82 and is connected to the upper end of the back frame 14 via a pair of left and right holders 16 shown in Fig. 1.

[0085] A thick, annular stopper portion 82S is formed at the upper end of the bushing 82 shown in Figure 13. A locking member 66 similar to the locking member 66 in the fourth embodiment (see Figure 9) is provided at the stopper portion 82S. A cylindrical first body portion 82A is formed continuously below the intermediate portion between the inner and outer circumferential ends of the stopper portion 82S, and a cylindrical second body portion 82C having a smaller diameter than the first body portion 82A is formed below the first body portion 82A. The lower end of the first body portion 82A and the upper end of the second body portion 82C are connected by a connecting portion 82B. A locking portion 82K is formed at the lower end of the second body portion 82C.

[0086] A locking device 84 serving as a locking mechanism is incorporated into the inner circumferential side of the first body portion 82A inside the upper part of the bushing 82. In the present embodiment, the locking device 84 is, for example, integrally molded with the bushing 82 during injection molding of the bushing 82. The locking device 84 includes a tubular member 86 made of steel and formed into a cylindrical shape. The leg portion 62A of the headrest stay 62 is inserted into the tubular member 86. A restricting protrusion 86A serving as a restricting portion that protrudes radially inward around the entire circumference is formed on the upper end of the tubular member 86, for example.

[0087] A steel fastening member 88 is housed inside the tubular member 86. Fig. 14 shows a plan view of the fastening member 88 alone. As shown in Figs. 13 and 14, the fastening member 88 is C-shaped in plan view along the outer periphery of the leg portion 62A of the headrest stay 62, and fastens the leg portion 62A from the outer periphery side by its restoring force.

[0088] To provide further explanation, the inner diameter of the fastening member 88 shown in Fig. 14 before assembly is set to be smaller than the outer diameter of the leg portion 62A of the headrest stay 62 shown in Fig. 13. When the leg portion 62A of the headrest stay 62 is inserted into the fastening member 88, the fastening member 88 deforms within its elastic range to fasten the leg portion 62A of the headrest stay 62.

[0089] 13, a plurality of fastening members 88 are provided and aligned in the axial direction of the leg portion 62A. A stopper 89 serving as a restricting portion is disposed adjacent to the lower side of the lowest fastening member 88. The stopper 89 is fixed to the fastening member 88 and, together with the restricting protrusion 86A described above, restricts the up and down movement of the fastening member 88. The locking device 84, which includes the tubular member 86, the fastening member 88, and the stopper 89, is configured to allow the leg portion 62A to move up and down while maintaining the shape of the fastening member 88.

[0090] According to the present embodiment described above, the tightening member 88 tightens the leg portion 62A from the outer periphery by its restoring force while its vertical movement is restricted by the restricting protrusions 86A and the stopper 89. As a result, a frictional force is generated between the leg portion 62A and the tightening member 88, and the leg portion 62A is held in place. Furthermore, when a force is applied to move the leg portion 62A of the headrest stay 62 up or down to adjust the height of the headrest 20 (see FIG. 1), the locking device 84 restricts the vertical movement of the tightening member 88 by the restricting protrusions 86A and the stopper 89, while allowing the leg portion 62A to move up or down while maintaining the shape of the tightening member 88. Therefore, with a simple configuration, it is possible to continuously adjust the height of the headrest 20 (see FIG. 1) in the seat vertical direction.

[0091] Furthermore, according to this embodiment, a plurality of fastening members 88 are provided so as to be aligned in the axial direction of the leg portion 62A of the headrest stay 62. Here, by changing the number of fastening members 88, it is possible to change the friction load between the leg portion 62A of the headrest stay 62 and the locking device 84 side, and therefore the operating force required for the up and down movement of the headrest stay 62 can be easily adjusted.

[0092] [Modification of the sixth embodiment] Next, a modification of the sixth embodiment will be described with reference to FIG. The modified example of the sixth embodiment is not an embodiment of the present invention but a reference example. A headrest support structure 80A according to a modification of the sixth embodiment is shown in a vertical cross section in Fig. 15. The headrest support structure 80A according to the modification shown in Fig. 15 has the same configuration as the sixth embodiment, except for the points described below.

[0093] As shown in FIG. 15, a headrest support portion structure 80A includes a bushing 83 instead of the bushing 82 (see FIG. 13) of the sixth embodiment. The bushing 83 has a similar configuration to the bushing 82 of the sixth embodiment, except that a stopper portion 83S is provided instead of the stopper portion 82S (see FIG. 13) of the bushing 82 of the sixth embodiment. Therefore, for convenience, components of the bushing 83 that are similar to those of the bushing 82 of the sixth embodiment are denoted by the same reference numerals and will not be described. The stopper portion 83S is formed in a thick, annular shape, and its outer and inner diameters are similar to those of the stopper portion 82S (see FIG. 13) of the sixth embodiment, but no member equivalent to the locking member 66 (see FIG. 13) of the sixth embodiment is provided. The connection position of the first body portion 82A to the stopper portion 83S is the same as the connection position of the first body portion 82A to the stopper portion 82S in the sixth embodiment (see FIG. 13 for both).

[0094] In the configuration of the sixth embodiment, as shown in Fig. 13, a notch 62A1 is formed on the lower end side of the leg portion 62A of the headrest stay 62 to prevent the leg portion 62A from coming off in the event of a collision (impact), but in a modified example of the sixth embodiment, a stopper 63X shown in Fig. 15 is provided instead of the notch 62A1. The stopper 63X can be joined to the lower end side of the leg portion 63A by bolting, welding, or the like, for example, after the headrest stay 63 is assembled. The stopper 63X includes a large-diameter portion 63X1 having a diameter larger than that of the general portion 63A1 of the leg portion 63A, and an inclined step portion 63X2 whose diameter gradually decreases from the upper end of the large-diameter portion 63X1 to the same diameter as the general portion 63A1 of the leg portion 63A. In a modified example of the sixth embodiment, when the headrest stay 63 is pulled up by more than a predetermined amount during a collision or the like, the stopper 63X hits the bottom side of the bush 82, stopping the leg 63A from rising, thereby preventing the leg 63A of the headrest stay 63 from coming loose.

[0095] [Seventh embodiment] next , th The headrest support structure according to the seventh embodiment will be described with reference to FIGS. The seventh embodiment is not an embodiment of the present invention but a reference example. FIG. 16 shows a vertical cross-sectional view of a headrest support structure 90 according to a seventh embodiment, and FIG. 17 shows an exploded cross-sectional view of a portion of the headrest support structure 90.

[0096] As shown in Fig. 16, a headrest support structure 90 according to the seventh embodiment has a configuration in which the locking device 30 in the headrest support structure 60 according to the fourth embodiment shown in Fig. 9 is replaced with the locking device 84 in the headrest support structure 80 according to the sixth embodiment shown in Fig. 13. Therefore, in the seventh embodiment, components that are substantially similar to those in the fourth embodiment and those in the sixth embodiment are denoted by the same reference numerals, and descriptions thereof will be omitted. Note that in the seventh embodiment, the locking device 84 has the same size and is located in the same position as the locking device 30 in the fourth embodiment shown in Fig. 9.

[0097] Here, the assembly of the headrest support structure 90 shown in Fig. 16 will be described. First, the locking device 84 is inserted from below into the upper bush 64 shown in Fig. 17 (see arrow S3). Next, the lower bush 70 is brought closer to the upper bush 64 and the locking device 84 from below (see arrow S4) so ​​that the engaging claw 72A of the lower bush 70 engages with the engaging recess 68 of the upper bush 64. Finally, as shown in Fig. 16, the leg 62A of the headrest stay 62 is inserted from above so as to pass through the axial centers of the upper bush 64, the locking device 84, and the lower bush 70, thereby obtaining the headrest support structure 60 shown in Fig. 16.

[0098] According to the configuration of the seventh embodiment described above, the same actions and effects as those of the sixth embodiment can be obtained, and in addition, the locking device 84, the upper bush 64, and the lower bush 70 can be easily disassembled.

[0099] [Eighth embodiment] Although not shown in the figure, , th As an eighth embodiment, instead of the locking device 30 in the fifth embodiment shown in FIG. 12, a locking device 84 in the sixth embodiment shown in FIG. 13 may be directly joined to the upper frame 14A (see FIG. 12). The eighth embodiment is not an embodiment of the present invention but a reference example.

[0100] [Ninth embodiment] next 、 A headrest supporting portion structure according to a ninth embodiment will be described with reference to Figs. 18 to 20D. The ninth embodiment is not an embodiment of the present invention but a reference example. Components that are substantially the same as those in the first embodiment are given the same reference numerals and descriptions thereof will be omitted.

[0101] Fig. 18 shows a simplified view of the upper part of a vehicle seat 98 equipped with a headrest support structure 100 according to a ninth embodiment, as viewed obliquely from above and in front. Of the pair of legs 22A of the headrest stay 22 shown in Fig. 18, one leg 22A (22AL) can be locked and unlocked, while the other leg 22A (22AR) can freely move up and down. Hereinafter, for convenience, one leg 22A (22AL) will be simply abbreviated as leg 22AL, and the other leg 22A (22AR) will be simply abbreviated as leg 22AR.

[0102] A cylindrical metal holder 102 is fixed by welding to the front portion of the seat width direction extending portion 14A1 of the upper frame 14A in correspondence with the non-lockable leg portion 22AR. A cylindrical resin bushing 104 is inserted into the holder 102. The leg portion 22AR is inserted into the bushing 104.

[0103] Meanwhile, a cylindrical metal holder 106, whose upper end is positioned lower than the holder 102, is fixed by welding to the front portion of the seat widthwise extending portion 14A1 of the upper frame 14A in correspondence with the lockable leg portion 22AL. A cylindrical resin bushing 108 is inserted into the holder 106. A locking device 110 serving as a locking mechanism is provided above the holder 106 and the bushing 108. Note that components of the locking device 110 are omitted as appropriate in FIG. 18.

[0104] The locking device 110 includes an operating lever 112 as an operating member through which the leg 22AL passes and which is rotatable about the axis of the leg 22AL. The locking device 110 is configured so that when the operating lever 112 is rotated in one direction (see arrow R1), the locking device 110 unlocks the leg 22AL, and when the operating lever 112 is rotated in the other direction (see arrow R2), the locking device 110 locks the leg 22AL.

[0105] Next, a specific configuration of the locking device 110 will be described with reference to FIGS. 19A to 19E.

[0106] Fig. 19A shows a schematic horizontal cross-sectional view of a state in which locking device 110 locks leg portion 22AL. Note that leg portion 22AL is actually formed in a hollow cylindrical shape, but for ease of viewing, in Fig. 19A it is hatched as if it were a solid cylindrical body (the same applies to Figs. 19B to 19E).

[0107] 19A, the locking device 110 includes a spring member 114 as a tightening member having a portion 114B that is annular in plan view along the outer periphery of the leg portion 22AL. The spring member 114 is wound around the outer periphery of the leg portion 22AL, with one end serving as a fixed end 114A that is engaged and fixed to an engaging portion 112B of the operating lever 112 and the other end serving as a free end 114C, and biases the leg portion 22AL to a locked state in which the leg portion 22AL is tightened from the outer periphery by a restoring force. Note that the engaging portion 112B is, for example, a portion that is formed integrally with the operating lever 112, and rotates integrally with the operating lever 112 when the operating lever 112 rotates.

[0108] The locking device 110 also includes a switching mechanism 116 , which has a release block (an element also known as a “piece”) 117 and a cam member 118 .

[0109] The release block 117 is disposed near the free end 114C of the spring member 114 and is rotatably supported on a shaft 112C that is parallel to the leg portion 22AL. As an example, the shaft 112C is formed integrally with the operating lever 112. A predetermined frictional resistance exists between the release block 117 and the shaft 112C to prevent the release block 117 from rotating inadvertently. The release block 117 has a shape that has a longitudinal direction in a plan view, and the shaft 112C passes through its central region. In addition, the lower part of the release block 117 on the side facing the free end 114C of the spring member 114 in the state shown in FIG. 19A and the diagonal side (upper right side in the figure) thereof are arc-shaped.

[0110] The cam member 118 is fixed to the bushing 108 via a plate 119 shown in FIG. 18. As a result, the cam member 118 shown in FIG. 19A is configured not to rotate even when the operating lever 112 is rotated. The cam member 118 includes a disk portion 118A that is circular in a plan view, and an unlocking cam portion 118B and a re-locking cam portion 118C that protrude from the outer periphery of the disk portion 118A in a plan view. The unlocking cam portion 118B is formed in a roughly fan shape and is a component that deforms the spring member 114 via the release block 117 to release the lock. The re-locking cam portion 118C is also formed in a roughly fan shape and is a component that executes re-locking by the spring member 114 via the release block 117. An outer circumferential arc portion 118B1 in a plan view of the unlocking cam portion 118B and an outer circumferential arc portion 118C1 in a plan view of the re-locking cam portion 118C are set at positions closer to the axis of the leg portion 22AL than the shaft 112C.

[0111] Here, unlocking and relocking by the locking device 110 will be described.

[0112] FIG. 19B is a schematic horizontal cross-sectional view showing a state in which the operating lever 112 has been operated in the unlocking direction (one direction (see arrow R1)) from the state in FIG. 19A. In this state, the release block 117 is in contact with the side wall surface 118B2 of the unlocking cam portion 118B and is about to rotate clockwise in the figure. When the operating lever 112 is further operated in the unlocking direction from the state in FIG. 19B, the release block 117 rotates by approximately 90° as shown in FIG. 19C, pushing the free end 114C of the spring member 114, causing the spring member 114 to expand slightly in diameter, thereby achieving an unlocked state. At this time, the occupant can move the headrest stay 22 up and down.

[0113] Next, when the operating lever 112 is operated from the state shown in FIG. 19C in the direction opposite to the unlocking direction (the other direction (see arrow R2)), the state shown in FIG. 19D is reached. In this state, the release block 117 maintains a state in which its longitudinal direction is aligned with the circumferential direction of the leg 22AL, and the unlocked state is maintained. When the operating lever 112 is further operated from the state shown in FIG. 19D in the direction opposite to the unlocking direction, the state shown in FIG. 19E is reached. In this state, the release block 117 abuts against the side wall surface 118C2 of the re-lock cam portion 118C and attempts to rotate counterclockwise in the figure. When the operating lever 112 is further operated from the state shown in FIG. 19E in the direction opposite to the unlocking direction, the state shown in FIG. 19A is reached. In this state, the release block 117 does not press the free end 114C of the spring member 114, so the spring member 114 tightens the leg 22AL from the outer circumferential side, and the lock state is restored. Incidentally, even if a load of 500 N is applied in this state in a height retention test as stipulated by headrest regulations, the frictional force of the spring member 114 prevents the headrest 20 from moving up or down.

[0114] As described above, the switching mechanism 116 presses the free end 114C of the spring member 114 as shown in Fig. 19C in response to the rotation of the operating lever 112 in one direction (see arrow R1), thereby expanding the diameter of the spring member 114 and releasing the locked state, and releases the pressure on the free end 114C of the spring member 114 as shown in Fig. 19A in response to the rotation of the operating lever 112 in the other direction (see arrow R2), thereby causing the spring member 114 to elastically return to the locked state. The locking device 110 is configured to allow the leg portion 22AL of the headrest stay 22 to move up and down by changing the shape of the spring member 114.

[0115] 20A to 20D, an example of assembling the locking device 110 will be outlined. As shown in Fig. 20A, the seat width direction extending portion 14A1 of the upper frame 14A is provided with a crushed portion 14X for attaching the holder 106 (see Fig. 20B).

[0116] First, the holder 106 shown in FIG. 20B is welded to the crushed portion 14X of the upper frame 14A shown in FIG. 20A. Next, as shown in FIG. 20C, the bushing 108 is inserted into the holder 106, and multiple engagement claws 108A of the bushing 108 protrude upward from the holder 106. Next, as shown in FIG. 20D, predetermined portions (engagement portions with holes) of a plate 119 at the bottom of the locking device 110 are engaged with the engagement claws 108A provided on the upper part of the bushing 108. Note that, for ease of viewing, the internal components of the locking device 110 are not shown in FIG. 20D. The plate 119 is formed with holes 119H through which the leg portions 22AL (see FIG. 18) of the headrest stay 22 are inserted. After the step shown in FIG. 20D, a back pad (not shown), the trim cover 18 shown in FIG. 18, and the operating lever 112 are attached, and the assembly of the locking device 110 is completed.

[0117] According to the ninth embodiment described above, the height of the headrest 20 in the seat up-down direction can also be easily adjusted in a stepless manner.

[0118] [Supplementary explanation of the embodiment] 1 to 10, multiple sets of balls 34, 46, 56 aligned in the circumferential direction are arranged in the axial direction of the leg portions 22A, 52A of the headrest stays 22, 52, but a configuration in which only one set of balls aligned in the circumferential direction is provided may also be adopted. Also, in the sixth and seventh embodiments shown in Figures 13 to 17, multiple fastening members 88 are provided so as to be aligned in the axial direction of the leg portions 62A of the headrest stay 62, but a configuration in which only one fastening member is provided may also be adopted.

[0119] The above-described embodiment and the above-described modifications can be implemented in appropriate combinations.

[0120] The above describes one example of the present invention, but the present invention is not limited to the above, and it goes without saying that the present invention can be implemented in various modified forms within the scope of the gist of the present invention. [Explanation of symbols]

[0121] 11 Headrest support structure 20A Headrest body 22 Headrest stay 22A Legs 32 Cylindrical member 32B tapered section 32N Inner surface of cylindrical member 32X recess 32Z Lower end of cylindrical member 34 balls 40 Headrest support structure 42 First bush (cylindrical member) 42B tapered section 42N Inner surface of first bush (inner surface of cylindrical member) 42X recess 46 balls 48 Ring member 50 Headrest support structure 52 Headrest stay 52A Legs 52G Outer surface of leg 52T tapered section 52X recess 54 First bush (cylindrical member) 56 balls 58 Ring member 60 Headrest support structure 62 Headrest stay 62A Legs 63 Headrest stay 63A Legs 64 Upper bush 70 Lower bush 74 Headrest stay 74A Legs 76 Headrest support structure 80 Headrest support structure 80A Headrest support structure 84 Locking device (locking mechanism) 86 Cylindrical member 86A Restriction protrusion (restriction part) 88 Fastening member 89 Stopper (regulating part) 90 Headrest support structure 100 Headrest support structure 110 Locking device (locking mechanism) 112 Operating lever (operating member) 114 Spring member (fastening member) 114A fixed end 114B Part that is circular in plan view 114C Free end 116 Switching Mechanism

Claims

1. a headrest stay including a leg portion extending downward from inside the headrest body; a cylindrical member formed in a cylindrical shape and through which the leg portion is inserted; a recess formed in an annular and concave shape along a circumferential direction on one of an inner circumferential surface of the cylindrical member and an outer circumferential surface of the leg portion; a pair of upper and lower tapered portions inclined so as to gradually narrow the gap between the upper and lower opposing portions from the opening end side of the recessed portion toward the recessed bottom side; a plurality of balls arranged in the recess and aligned in the circumferential direction of one of the balls, which are in contact with both the cylindrical member and the leg portion and hold the leg portion by frictional force, and when the leg portion is moved up and down, when one of the balls moves upward relative to the other of the inner peripheral surface of the cylindrical member and the outer peripheral surface of the leg portion, the balls are rotatable while their downward relative displacement with respect to the one of the balls is restricted by the lower tapered portion of the pair of upper and lower tapered portions, and when one of the balls moves downward relative to the other of the balls, the balls are rotatable while their upward relative displacement with respect to the one of the balls is restricted by the upper tapered portion of the pair of upper and lower tapered portions; A headrest support structure having the following features.

2. 2. The headrest support structure according to claim 1, wherein the plurality of balls arranged in one circumferential direction are arranged in a plurality of sets in the axial direction of the leg portion.

3. 3. The headrest support structure according to claim 1, further comprising a ring member formed in an endless string shape that passes through the centers of the plurality of balls arranged in one circumferential direction, the ring member having elasticity and capable of elastically returning to the assembled shape when elastically deformed.

4. an upper bushing into which the leg portion is inserted and which is provided on the outer circumferential side of the cylindrical member; a lower bushing adjacent to the lower end of the tubular member on the lower side, through which the leg portion is inserted, and provided on the lower end side of the upper bushing in an engageable and disengageable manner; The headrest support structure according to any one of claims 1 to 3, comprising:

Images